Hitherto, management of data stored in data recording region of information recording media such as semiconductor memory, magnetic disk or magneto-optical disk has been realized by a file system. In the file system, the data recording region is divided into sectors which are minimum access units, or clusters each of which is a set of sectors, and one or more clusters are managed as a file.
As a file system used conventionally, FAT (File Allocation Table) file system is known (see Reference 1). The FAT file system is a general file system used in personal computers and other information appliances, and is characterized by unified management of physical storing position of data composing a file by a table called FAT. An information recording medium of which data is managed by a file system such as FAT file system can share files between different devices interpreting the same file system, so that data can be exchanged between devices.
However, aside from FAT file system, file systems include various types such as FAT32 file system, NTFS (NT file system), UDF (universal disk format), and file systems interpreted by devices are varied depending on devices. Hence, even if the same information recording medium is shared by a plurality of devices, when file systems used for storing data are different, data cannot be exchanged between devices.
To solve this problem, it has been proposed to provide the information recording medium with a region for storing plural kinds of file system management information, and a region for storing common file data (see Reference 2). In this conventional method, after the information recording medium is inserted into the device, the file system to be used is selected, and the beginning address of the region storing the corresponding file system management information is set as address 0, and it is attempted to access the file system management information. Thus, by selecting and using any one of the plural kinds of file system management information, data can be exchanged by using a common information recording medium on devices interpreting different file systems.                Reference 1: ISO/IEC9293, “Information Technology—Volume and file structure of disk cartridges for information,” 1994        Reference 2: JP, 08-272541, A(Problems to be Solved by the Invention)        
However, the prior art has the following problems. In the conventional region management method, plural kinds of file system management information are stored in individual file system types, and only one set of file data common to each file system is stored. Accordingly, when handling files having same data by different file systems, it is not needed to store a plurality of data entities, and data recording regions can be curtailed. In this method, however, upon editing one file, plural kinds of file management information must be changed at the same time, and files can be edited only by a device capable of interpreting all file system management information.
Between a plurality of devices recognizing different file systems, upon sharing information recording medium, if information recording medium formatted by a certain file system is used in a device capable of recognizing only other file system, original information in the information recording medium may be broken.
This problem occurs similarly, not only upon using the same information recording medium by different devices, but also upon using one information recording medium by the same device, as far as the device is capable of recognizing a plurality of file systems.
The invention is devised in the light of the above problem, and it is hence an object to present an information recording medium for maintaining data interchangeability or preventing malfunction, in the case different in the type or number of file systems capable of interpreting in each device, or in the case capable of recognizing a plurality of file systems in the same device, and its region management system.
(Method for Solving Problems)
A first region management method of the invention is a method of managing an information recording medium having a data recording region for storing data, the data stored in the recording medium being managed as a file by a file system. In the region management method, the data recording region is divided into a plurality of recording regions each managed by different file systems individually. A command is received from outside of the information recording medium. One of the divided recording regions is selected according to the received command, as a region accessible from outside of the information recording medium.
In the first region management method, a validity flag indicating a region which is valid presently among the plurality of divided recording regions may be set in the information recording medium. By referring to the validity flag prior to access to the data recording region in the information recording medium, the one of the divided recording regions to be accessible may be selected.
In the first region management method, the validity flag may be set to a specified value when initializing the information recording medium, and afterward the validity flag may be set again according to a command received from outside of the information recording medium.
In the first region management method, size of each divided recording region may be stored in the information recording medium, and the size of each divided recording region may be changed according to a command received from outside of the information recording medium.
In the first region management method, the information recording medium may be managed by file systems each constructed in each divided recording region and include a protect region and a user data region. The protect region may be accessible by a device connected to the information recording medium only when the device is authorized. The user data region may be accessible from the device independently of authorization.
A second region management method is a method of managing an information recording medium having a data recording region for storing data, the data stored in the recording medium being managed as a file by a file system. In the second region management method, the data recording region is divided into a plurality of recording regions each managed by different file systems individually. A plurality of storage blocks is stored in a consecutive recording region in the information recording medium. The storage block has constant data size, and stores a partition table. The partition table is provided to each divided recording region, and is information about a region management which is used by each file system of each divided region. A valid block number indicating a storage block which includes the partition table for a region in the divided recording regions that is accessible from outside of the recording medium is stored. According to a command received from outside of the recording medium, by referring to the validity block number, one storage block is selected from a partition table storage block, and a partition table is determined to be accessible from outside of the information recording medium.
In the second region management method, the partition table included in the selected storage block may be disposed at the beginning of a logical address space of the information recording medium.
In the second region management method, the partition table may include start address of the region managed by the file system and size of the region, and regions specified by the respective partition tables do not overlap each other.
The data recording region may be managed by file systems each constructed in each divided recording region, and include a protect region and a user data region. The protect region may be accessible by a device connected to the information recording medium only when the device is authorized. The user data region may be accessible from the device independently of authorization. The partition table information may be provided to the user data region and protect region. Regarding the same divided recording region, a partition table for the user data region and a partition table for the protect region may be managed in pairs.
A first information recording medium of the invention is a recording medium having a data recording region for storing data. The recording region is divided into a plurality of regions. A different file system for managing data stored in each region is constructed in each divided region. The information recording medium includes a region information storage section that stores a validity flag showing a region in the divided regions that is accessible from an external device, and an access region judging section that selects one valid region by referring to the validity flag and allows access to the selected region by the external device.
A second information recording medium of the invention is a recording medium having a data recording region for recording data. The data recording region is divided into a plurality of recording regions each managed by different file system. The information recording medium includes a partition table storage section that stores a plurality of storage blocks for storing a partition table which is information about region management used by the file system in each divided region, a command receiving section that receives a command from outside of the information recording medium, a region information storage section that stores valid block number indicating a storage block of the plurality of storage blocks in the partition table storage section, the storage block including the partition table which is accessible from an external device, and an access region judging section that selects one storage block from the partition table storage section with reference to the valid block number, and determines the partition table which is accessible from the external device, on the basis of a command received from outside of the information recording medium.
A third region management method of the invention is a method of managing an information recording medium having a data recording region for storing data, the data stored in the recording medium being managed as a file by a file system. The third region management method includes, storing a plurality of types of sizes of the data recording region accessible from outside of the information recording medium, and changing the size of accessible region according to a command receiving from outside of the information recording medium.
In the third region management method, valid region information may be stored. The valid region information is information indicating the size which is presently valid in a plurality of types of sizes of data recording regions accessible from outside of the information recording medium. Prior to access to the data recording region in the information recording medium, by referring to the valid region information, the size of accessible region may be recognized to judge possibility of access.
In the third region management method, the valid region information may be set to one of the plurality of sizes stored, simultaneously with initialization of the information recording medium, and it may be set again by a command received from outside of the information recording medium.
In the third region management method, the stored size of each region can be changed by a command received from outside of the information recording medium.
In the third region management method, the information recording medium may include a protect region and a user data region. The protect region may be accessible by a device connected to the information recording medium only when the device is authorized. The user data region may be accessible from the device independently of authorization.
A third information recording medium of the invention is an information recording medium having a data recording region for recording data. The recording medium includes a region information storage section and an access judging section. The region information storage section stores a plurality of types of sizes of the data recording region accessible from outside of the information recording medium, and valid region information which is information indicating the size which is presently valid in a plurality of types of sizes of data recording regions accessible from outside of the information recording medium. Prior to access to the data recording region in the information recording medium, the access judging section recognize the size of accessible region by referring to the valid region information, and judges possibility of access.
In the third information recording medium, a plurality of types of region sizes accessible from outside of information recording medium is stored in the information recording medium, and the size of region may be changed over by a command received from outside of the information recording medium. Thus, data interchangeability between devices can be maintained and malfunction can be prevented, even when the devices are different in type and number of file systems which the devices can interpret.
A fourth region management method of the invention is a method of managing an information recording medium having an data recording region for storing data, the data stored in the recording medium being managed as a file by a file system. The fourth region management method including, storing information providing size of data recording region to a specific register, setting the information providing size of data recording region in the register simultaneously with initialization of the information recording medium to a specific value smaller than the actual size of the data recording region, and setting again, according to a command received from outside of the information recording medium, the information providing size of data recording region in the register to an actual size of the information recording medium.
In the fourth region management method, when setting the size of the data recording region in the register at 0 kB, the information recording medium may prevent reception of a data read command or data write command from outside of the information recording medium.
In the fourth region management method, the information recording medium may include a protect region and a user data region. The protect region may be accessible by a device connected to the information recording medium only when the device is authorized. The user data region may be accessible from the device independently of authorization. At this time, the information providing size of data recording region in the register is set to provide the size of the user data region.
A fourth information recording medium of the invention is an information recording medium having a data recording region for recording data. The information recording medium includes a register that stores information providing size of data recording region to a specific register, a command receiver that receives a command from outside of the information recording medium, and an access region judging section that sets the information providing size of data recording region in the register simultaneously with initialization of the information recording medium to a specific value smaller than the actual size of the data recording region, and sets again, according to a command received from outside of the information recording medium, the information providing size of data recording region in the register to an actual size of the information recording medium.
In the fourth information recording medium, size information of the data recording region is stored in a specific register. Simultaneously with initialization of information recording medium, the size of the data recording region in the register is set to a specific value. Size of data recording region in the register is set again to actual size of the data recording region by a command received from outside of the information recording medium. Thus, data interchangeability between devices can be maintained and malfunction can be prevented, even when the devices are different in type and number of file systems which the devices can interpret.
(More Advantageous Effects than in the Prior Art)
According to the invention, the data recording region in the information recording medium is divided into a plurality of regions managed by different file systems, a plurality kinds of information of each region starting position and size are stored in the information recording medium, and by selecting one accessible region by command entering from outside of the information recording medium, a plurality of independent file systems can be constructed in one information recording medium, and if the type or number of file systems capable of interpreting differs in each device, data interchangeability between devices can be maintained, and malfunction can be prevented.
In the information recording medium, a plurality of storage block storing partition table information as information relating to region management used by file system are stored in the information recording medium, and by selecting one storage block by command entering from outside of the information recording medium, and disposing it at the beginning of data recording region, a plurality of independent file systems can be constructed in one information recording medium, and if the type or number of file systems capable of interpreting differs in each device, data interchangeability between devices can be maintained, and malfunction can be prevented.